Puncture sealing agent

ABSTRACT

The present invention is directed to provide a puncture-sealant that can maintain high sealing ability and is excellent in practicality. The invention is a puncture-sealant for sealing a hole in a punctured tire, the puncture-sealant including: ( 1 ) at least one type of rubber latex selected from the group consisting of SBR latex, NBR latex, carboxyl-modified SBR latex and carboxyl-modified NBR latex; ( 2 ) an antifreezing agent; and ( 3 ) at least one of a short fiber or a resin adhesive that is compatible with the rubber latex.

TECHNICAL FIELD

The present invention relates to a puncture-sealant for use in sealing ahole in a punctured tire.

BACKGROUND ART

As a repairing agent for sealing a punctured site of a tire, variouspuncture-sealants are known (see, for example, Patent Document 1). Suchpuncture-sealants mainly contain a colloid dispersion-system polymer inan aqueous medium (latex). Examples of the latex to be used includepolyethylene-butadiene latex, polyvinylacetate latex, acrylic copolymerlatex, nitrile latex and polychloroprene latex.

In order to introduce such a puncture-sealant into a tire and charge aninternal pressure to enable some running, a device, such as a spray can,is conventionally used, which includes a pressure-resistant containerfor storing a puncture-sealant containing a liquefied gas as a pressuresource. As the liquefied gas, a gas mixture of propane and butane ismainly used. In rare cases, chlorofluorocarbons may also be used. Oneend of a hose is connected to the spray can at an outlet valve thereof,and a threaded adapter for a tire valve is attached to another end ofthe hose.

When a tire is punctured, the puncture-sealant is sprayed from the spraycan through the tire valve into the tire. Along with the spraying of thepuncture-sealant, an internal pressure of the tire is recharged withfuel gas of a particular pressure of a level depending on an amount ofleaked gas. At this time, with the puncture-sealant being sprayed intothe tire to seal the damage, the tire generally travels severalkilometers, although the distance varies depending on the degree ofdamage of the tire.

In another device, a puncture-sealant is stored in a compressive flaskto be connected, via an adapter, to a tire valve, whose insert has beenremoved in advance. The puncture-sealant is blown into a tire by acompressive action of the flask. After the valve insert is inserted, thetire is inflated again to a specific internal pressure with a help of acarbon dioxide cartridge.

However, puncture-sealants currently in use are not completelysatisfactory. Such puncture-sealants are removed due to mechanicalaction relatively soon, and are slow to effect sealing of a puncturehole. Therefore, use of the puncture-sealants necessitates significanttime for preparatory running before completing sealing and making thepunctured tire ready for running.

There is also a problem with conventional devices for introducing apuncture-sealant into a tire and pumping up the tire. Spray canscontaining the fuel gas mixture of propane and butane cannot be usedsatisfactory unless they are cooled down to about 0° C., depending on amixing ratio thereof. Further, the gas mixture of propane and butane isinflammable and explosive. Chlorofluorocarbons exert an adverse effecton the environment. In addition, all of known fuel gases are subjectedto limitation in an amount thereof usable at a time of puncture.

As a puncture-sealant and a pumping-up device for a tire that can solvethe above-described problems, Patent Document 1, for example, disclosesa puncture-sealant containing rubber latex, which is solely composed ofnatural rubber latex, and a resin adhesive that is compatible with thenatural rubber latex, as well as a sealing pumping-up device using thispuncture-sealant. However, recently, allergic reactions caused by acertain protein contained in natural rubber latex are becoming aproblem. Specifically, some people may suffer from symptoms likeurticaria, such as itching, red scars and swelling, at sites of skin oftheir hands, faces, or the like, where the natural rubber has adhered.Further, some people, who have inhaled natural rubber latex splashed inair, may suffer from symptoms such as asthma, rhinitis and/orconjunctivitis. That is, in a case where a puncture-sealant containingnatural rubber is used, the puncture-sealant may cause health problemson an operator due to allergic reactions when the puncture-sealantaccidentally adheres to the hand, the face, or the like of the operator,or the operator accidentally inhales the puncture-sealant splashing withthe gas during repair of a punctured tire.

Moreover, ammonia is usually added to natural rubber latex as a pHcontroller to adjust the pH of the natural rubber latex around a rangefrom 9 to 10 to ensure stability of the latex. Therefore, duringrepairing of a punctured tire, a strong irritating odor is exuded fromthe puncture-sealant. This makes the working environment not good for anoperator and may exert adverse effects to health of the operative.

In recent years, with respect to natural rubbers (NR) such as describedabove, improvements by developing deproteinized NRs are in progress.Although such improvements of natural rubbers effectively improveallergic reactions of human bodies, they do not eliminate or reduce thestrong irritating odor when the natural rubbers are used aspuncture-sealants. Further, there have been attempts to use chemicalsother than ammonia as the pH controller for the natural rubbers.However, practically, it is difficult to obtain sufficient stability ofthe natural rubber latex contained in puncture-sealants by usingchemicals other than ammonia.

Puncture-sealants are required to have properties such as (1) puncturehole sealing ability, (2) ease of injection (the puncture-sealant shouldbe easily injected through a valve, or the like), (3) a certain degreeof antifreezing property (the puncture-sealant should not freeze when itis used at low temperature), (4) separation stability (thepuncture-sealant should not separate during a long-term storage), andthe like.

With conventional puncture-sealants as described above, latex, which isthe main component of the puncture-sealants, serves to ensure thesealing ability thereof. Further, an antifreezing agent serves to ensurethe antifreezing property, and a thickener and a pH controller serve toensure the ease of injection and the separation stability of thepuncture-sealants.

However, the above-described properties (1) to (4) are in a trade-offrelationship. For example, if a glycol content in a puncture-sealant isincreased, the antifreezing property of the puncture-sealant becomessufficient. However, in this case, since a relative latex content isdecreased, the sealing ability is lowered. That is, it is difficult toproduce a puncture-sealant sufficiently provided with all of theabove-described properties.

Among the above-described properties (1) to (4), the most importantproperty is the sealing ability. In recent years, in order to improvethe sealing ability, puncture-sealants containing fiber have been putinto practical use.

However, even in the puncture-sealants containing fiber, theabove-described properties are not sufficiently balanced. Namely, assuch puncture-sealants contain a large amount of fiber, viscositythereof is increased and the ease of injection is significantly lowered.

In other words, even with the puncture-sealants containing fiber, theideal design of mix for additives has not sufficiently been established.

In view of the foregoing, the present invention is directed to solve theabove-described conventional problems. Specifically, the invention isdirected to provide a puncture-sealant that can maintain a high sealingability and function excellent in actual use.

DISCLOSURE OF THE INVENTION

In order to achieve the above-described objectives, the presentinventors have found through intensive study that these objectives canbe achieved by the following invention.

Namely, the invention is a puncture-sealant for sealing a hole in apunctured tire, the puncture-sealant comprising:

(1) at least one type of rubber latex selected from the group consistingof SBR latex, NBR latex, MBR latex, carboxyl-modified SBR latex andcarboxyl-modified NBR latex;

(2) an antifreezing agent; and

(3) at least one of a short fiber and a resin adhesive that iscompatible with the rubber latex.

Further, the puncture-sealant of the invention preferably comprises oneor more aspects of the following aspects (1) to (11).

(1) A first aspect is that the resin adhesive is added to an aqueousdispersion of the rubber latex or an aqueous emulsion of the rubberlatex.

(2) A second aspect is that a content of the resin adhesive is within arange from 3 to 30% by mass.

(3) A third aspect is that a content of solid components is within arange from 5 to 70% by mass.

(4) A fourth aspect is that a content of the antifreezing agent iswithin a range from 5 to 50% by mass.

(5) A fifth aspect is that a viscosity of the puncture-sealant at leastbefore it is filled in the tire and at temperatures in the range from60° C. to −20° C. is within a range from 3 mPa·s to 6000 mPa·s.

(6) A sixth aspect is that a content of the short fiber is within arange from 0.1 to 5% by mass.

(7) A seventh aspect is that a length (L) of the short fiber is within arange of 0.05≦L≦10 mm and a diameter (D) of the short fiber is within arange of 1≦D≦100 μm.

(8) An eighth aspect is that a ratio (L/D) of the length (L) of theshort fiber to the diameter (D) of the short fiber is within a range of5≦L/D≦2000.

(9) A ninth aspect is that a specific gravity (S) of the short fiber iswithin a range of 0.8≦S≦1.4.

(10) A tenth aspect is that all or a part of the short fiber is treatedwith a solvent.

(11) An eleventh aspect is that the short fiber comprises one ofpolyester, polyethylene, nylon, polypropylene or a composite material oftwo or more types thereof.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating one example of a sealingpumping-up device used for filling a tire with a puncture-sealantaccording to an embodiment of the present invention; and

FIGS. 2A and 2B are schematic views illustrating another example of thesealing pumping-up device used for filling a tire with apuncture-sealant according to the embodiment of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A puncture-sealant of the present invention is a puncture-sealant forsealing a hole in a punctured tire, and comprising: (1) at least onetype of rubber latex selected from the group consisting of SBR latex,NBR latex, carboxyl-modified SBR latex and carboxyl-modified NBR latex(which rubber latex will occasionally be referred to simply as “rubberlatex” hereinafter); (2) an antifreezing agent; and (3) at least one ofa short fiber and a resin adhesive being compatible with the rubberlatex.

Hereinafter, each of the above components, and additives that may beoptionally added, will be described.

[Resin Adhesive]

A resin adhesive that is compatible with the above-described rubberlatex is to be used. As such a resin adhesive, for example, a terpeneresin such as terpenephenol resin or a butyl rubber material such aspolyisobutylene can be used.

In the present specification, the expression that the resin adhesive is“compatible” with the rubber latex means that the resin adhesive doesnot cause coagulation of the rubber latex at all, and that the resinadhesive is used to enhance an adhesive strength of the rubber latex toa tire. For example, the resin may be added to an elastomer that servesas a tackifier for a rubber film.

The puncture-sealant of the invention employs specific rubber latex thatdoes not contain natural rubber. Therefore, even if the puncture-sealantaccidentally adheres to the hand, the face, or the like, of an operatoror the operator accidentally inhales the puncture-sealant splashing witha gas during repair of a punctured tire, there is no risk of causinghealth problems due to allergic reactions, and therefore, the operatorcan safely carry out repair of a tire. Further, since the resin adhesivecontains no component that becomes an allergen, the operator can safelycarry out repair of a tire.

Furthermore, with the puncture-sealant of the invention, sufficientstability can be obtained without adding a chemical having an irritatingodor, such as ammonia, as a pH controller to the rubber latex.Therefore, such a strong irritating odor is not exuded from thepuncture-sealant during puncture repair, and a working environment foran operator is improved and adverse effects to health due to theirritating odor can be prevented.

Moreover, as a result of comparative tests conducted by the presentinventors, the puncture-sealant of the invention can exhibit excellentsealing ability for a punctured tire, even under conditions of hightemperature and low temperature, as well as under a wet condition, aswith puncture-sealants containing rubber latex composed solely ofnatural rubber.

As the terpenephenol resin, for example, an a-pinenephenol resin, adipentenephenol resin, a terpenebisphenol resin, or hydrogenatedproducts of these resins can be used. In addition, commerciallyavailable terpenephenol resins can also be used.

A resin adhesive content is preferably in a range from 3 to 30% by mass,more preferably in a range from 5 to 25% by mass, and even morepreferably in a range from 7 to 20% by mass. A resin adhesive contentwithin the range from 3 to 30% by mass can provide satisfactory sealingability in actual applications.

The resin adhesive is preferably added to an aqueous dispersion or anaqueous emulsion of the rubber latex, in view of improving the sealingability.

[Short Fiber]

Short fiber enters into and serves to cause clogging of a hole (adefective portion) created in a punctured tire, so that the hole can bequickly and reliably closed. A short fiber content in thepuncture-sealant is preferably in a range from 0.1% by mass to 5% bymass.

If the short fiber content is less than 0.1% by mass, an improvement inthe sealing ability obtained by adding the short fiber may not besufficient. On the other hand, if the short fiber content is more than5% by mass, the short fiber may be entangled and a viscosity may beincreased, lowering the ease of injection, so that it becomes difficultto sufficiently exhibit the above-described function of the short fiber.In other words, the sealing ability may be lowered.

The short fiber content is preferably in a range from 0.3 to 4% by mass,and more preferably in a range from 0.5 to 3% by mass.

In order to have the short fiber sufficiently exhibit theabove-described function, various designs are necessitated by the shortfiber. A specific gravity (S), a length (L), a diameter (D), and a ratioof length to diameter (L/D) of the short fiber are preferably in thefollowing respective ranges.

(1) Specific gravity (S): 0.8≧S≧1.4 (more preferably 0.9≧S≧1.3, and evenmore preferably 1.0≧S≧1.2).

If the specific gravity is less than 0.8, the short fiber may float andlong-term separation stability of the puncture-sealant may bedeteriorated. On the other hand, if the specific gravity is more than1.4, the short fiber may sink and long-term separation stability of thepuncture-sealant may also be deteriorated.

(2) Length (L): 0.05≧L≧10 mm (more preferably 0.08≧L≧8 mm, and even morepreferably 0.1≧L≧6 mm).

If the length is less than 0.05 mm, the effect of the short fibercausing clogging at a puncture defective portion, thereby improving thesealing ability, may not be sufficiently exhibited. On the other hand,if the length is more than 10 mm, the relative number of short fibers isreduced and the sealing ability may be deteriorated.

(3) Diameter (D): 1≧D≧100 μm (more preferably 3≧D≧80 μm, and even morepreferably 5≧D≧50 μm).

If the diameter (thickness) is less than 1 μm, the function of the shortfiber to cause the clogging, thereby improving the sealing ability, maynot sufficiently be exhibited. On the other hand, if the diameter ismore than 100 μm, the relative number of the short fiber is reduced andthe sealing ability may be deteriorated.

(4) Ratio of length to diameter (LID): 5≧L/D≧2000 (more preferably20≧L/D≧1600, even more preferably 50≧L/D≧1200, and particularlypreferably 100≧L/D≧300).

If the L/D is less than 5, the function of the short fiber to cause theclogging, thereby improving the sealing ability, may not sufficiently beexhibited. On the other hand, if the L/D is more than 2000, the shortfiber may be entangled to generate wads, and this may lead todeterioration of the sealing ability and the ease of injection.

It should be noted that the short fiber may be formed of a singlematerial having a certain shape, or the short fiber may be formed ofseveral types of materials having various shapes within theabove-described ranges.

The material of the short fiber is not specifically limited. However, itis preferable that the short fiber is formed of one of polyester,polyethylene, nylon, polypropylene, or a composite of two or morethereof. More preferably, the short fiber is formed of one ofpolyethylene, nylon, polypropylene, or a composite of two or morethereof. Using such a short fiber, better separation stability can beobtained.

It is preferable that all or a part of (preferably all of) the shortfiber is treated with a solvent such as a higher alcohol derivativeand/or a betaine surfactant. Through this treatment, the solvent acts asa surfactant to improve dispersibility of the short fiber.

This treatment may be performed before or after addition of the shortfiber to the puncture-sealant. Specifically, this treatment can beeffected by immersing the short fiber in the above-described solvent, orspraying the solvent onto the short fiber. As the higher alcoholderivative, for example, polyglycol polyester is preferable.

An amount of the solvent to be added (an amount of the solvent to beabsorbed by the short fiber through the above treatment) is preferablyin a range from 0.2 to 20% by mass, more preferably in a range from 0.5to 10% by mass, and even more preferably in a range from 1 to 6% by massof the short fiber. If the amount is too small, the effect of dispersingthe short fiber may be insufficient, resulting in the insufficienttreatment of the short fiber. On the other hand, if the amount is toolarge, no further improvement of the effect can be obtained.

[Rubber Latex]

In view of ensuring good sealing ability, as described above, the rubberlatex is at least one rubber latex selected from the group consisting ofSBR (styrene-butadiene rubber) latex, NBR (nitrile rubber) latex, MBR(acrylic rubber) latex, carboxy-modified NBR latex and carboxy-modifiedSBR latex.

[Antifreezing Agent]

The antifreezing agent is not specifically limited, and for example,ethylene glycol or propylene glycol can be used. An antifreezing agentcontent is preferably in a range from 5 to 50% by mass. If theantifreezing agent content is less than 5% by mass, the antifreezingproperty at low temperature may be insufficient. On the other hand, ifthe antifreezing agent content is more than 50% by mass, the amount ofglycol is larger than the amount of the rubber latex, whereby particlesof coagulated rubber latex may be present in glycol in a dispersed stateduring puncture repair. In this case, the sealing ability may beinsufficient. A preferable content of the antifreezing agent is within arange from 10 to 40% by mass.

In the puncture-sealant as described above, a content of solidcomponents (which solid components will occasionally be referred to as“solids” hereinafter) in the puncture-sealant is preferably in a rangefrom 5 to 70% by mass.

The “solid content” can be determined in the following manner. First,100 g of the puncture-sealant is left for 30 minutes at 200° C.Thereafter, a residual mass of the puncture-sealant is measured, and theresidual mass is divided by the initial mass of the puncture-sealant(the residual mass/the initial mass of the initial puncture-sealant).

If the solid content is less than 5% by mass, the ratio of the rubberlatex is decreased and it may become impossible to ensure sufficientsealing ability. If the solid content is more than 70% by mass,properties other than the sealing ability may not be sufficientlyensured.

An upper limit of the solid content within the above-described range ismore preferably 60% by mass, even more preferably 50% by mass, andparticularly preferably 40% by mass. A lower limit of the solid contentwithin the above-described range is more preferably 8% by mass, and evenmore preferably 10% by mass.

A viscosity of the puncture-sealant under the expected conditions ofactual use (at least before the puncture-sealant is filled into a tire,a temperature ranging from 60° C. to −30° C.) is preferably in a rangefrom 3 to 6000 mPa·s, more preferably in a range from 5 to 4500 mPa·s,even more preferably in a range from 8 to 3000 mPa·s, particularlypreferably in a range from 10 to 3000 mPa·s, and most preferably in arange from 15 to 1500 mPa·s.

If the viscosity is less than 3 mPa·s, the viscosity is too low and thepuncture-sealant may be spilled during injection thereof into the valve.If viscosity is more than 6000 mPa·s, drag during injection is large andthe ease of injection may be deteriorated. In addition, thepuncture-sealant may not sufficiently spread over the inner surface ofthe tire, preventing a high sealing ability from being obtained. Itshould be noted that the viscosity can be measured, for example, with aB-type viscometer. Further, a thickener can be added if a higherviscosity is desired. On the other hand, if a lower viscosity isdesired, the latex component can be decreased and an amount of water canbe increased to obtain a viscosity in a desired range.

The puncture-sealant of the invention can contain water for adjustingviscosity or for dilution. Further, commonly used additives such asdispersants, emulsifiers, foam stabilizers, or pH controllers, such ascaustic soda, may be added to the puncture-sealant.

According to the puncture-sealant of the invention, sufficient stabilitycan be obtained without adding a chemical having an irritating odor suchas ammonia as a pH controller to the rubber latex.

In addition, in order to achieve quick sealing and reliable sealing evenwith a large hole, one or more types of filler may be mixed in thepuncture-sealant. Examples of an employable stable filler includesilicic acid, chalk, carbon black, a synthetic resin reinforced withglass fiber, polystyrene particles, powdered rubber obtained bypulverizing a vulcanized product such as a tire, sawdust, moss rubberparticles, and foam particles for cut flowers. Among them, rubber powderbonded with silicic acid and a synthetic resin reinforced with glassfiber are particularly preferable fillers.

The filler may be directly added to the puncture-sealant. However, ifthe puncture-sealant cannot be introduced or is difficult to beintroduced through the valve without changing the size of the valve, dueto the size of the filler, the filler is generally introduced into atire when the tire is assembled on a rim such that sealing isaccomplished by the puncture-sealant being injected at the time ofpuncture of the tire.

A content of the filler to be added to the puncture-sealant is fromabout 20 to 200 g/liter, and more preferably from 60 to 100 g/liter.Alternatively, the filler is placed in a tire when assembling the tireon a rim.

As liquid components, a dispersant or an emulsifier for the resinadhesive, preferably water, may be added. A liquid resin adhesive mayoptionally be used.

The puncture-sealant can be produced, for example, by mixing theabove-described materials in a known method. In order to avoidoxidation, the puncture-sealant is preferably produced, stored andfilled in a nitrogen or rare gas atmosphere.

For puncture repairing using the puncture-sealant described above, aknown method can be applied. Specifically, first, a container filledwith the puncture-sealant is inserted into a valve port of a tire, andan adequate amount of the puncture-sealant is injected. Thereafter, thetire is rotated so that the puncture-sealant spreads over the innersurface of the tire and a puncture hole is sealed.

The puncture-sealant itself is introduced into the tire through use ofvarious pumping-up devices, such as a spray can containing a gas mixtureof propane and butane as a fuel gas, and inflates the tire again. Apumping-up device 20 as shown in FIG. 1 can provide especiallypreferable use of the puncture-sealant.

The pumping-up device 20 shown in FIG. 1 employs a small air compressor1 as the pressure source. The air compressor 1 is connected to a gasintroducing section 3 of a pressure-resistant container 4 via a hose 2.The gas introducing section 3 is formed as a riser tube extending toreach above a liquid surface of the puncture-sealant 6 contained in thepressure-resistant container 4, and the gas introducing section 3 can beclosed at a plug valve 5.

The pressure-resistant container 4 includes an outlet valve 7 fordischarging the puncture-sealant 6. One end of a hose 8 is connect tothe outlet valve 7, and another end of the hose 8 is attached to athreaded adapter 9, which is attached to a tire valve 10 with a screw.

The pressure-resistant container 4 includes filling stubs 12 and ajacket 11 filled with water. As required, calcium chloride as a heatsource may be filled in the filling stub 12. If the puncture-sealant 6freezes at low temperature, heat released by hydration of the heatsource heats up the puncture-sealant 6 to a usable temperature.

An electric cable 13 is connected to the air compressor 1, and a plug 14thereof is inserted, for example, into a cigarette lighter.

If a tire is punctured, the threaded adapter 9 is screwed on andattached to the tire valve 10 and the air compressor 1 is connect to thecigarette lighter, and the plug valve 5 is opened at the gas introducingsection 3 of the pressure-resistant container 4. Then, the compressedair introduced from the air compressor 1 through the gas introducingsection 3 into the pressure-resistant container 4 extrudes thepuncture-sealant 6 out from the outlet vale 7, so that thepuncture-sealant 6 is introduced into the tire through the tire valve10. As a result, the tire is inflated with air again to have apredetermined internal pressure. When this procedure is completed, thethreaded adapter 9 is removed from the tire valve 10 and the aircompressor 1 is turned off. After this, running in is immediatelycarried out over a certain distance to spread the puncture-sealant 6inside the tire to seal a puncture hole. Subsequently, the pumping-updevice 20 is connected again to pump up the tire until it has a requiredinternal pressure.

The puncture-sealant of the invention can also be used more preferablywith a pumping-up device 30 shown in FIGS. 2A and 2B. It should be notedthat, in the pumping-up device shown in FIGS. 2A and 2B, parts that arecommon with those of the pumping-up device 20 shown in FIG. 1 areassigned with the same reference numerals and explanations thereof areomitted.

The pumping-up device 30 includes a resin bottle 22 shown in FIG. 2A,which is a container for the puncture-sealant 6, and the air compressor1 shown in FIG. 2B as the pressure source. The bottle 22 contains thepuncture-sealant 6 of an amount necessary for a single repairing ofpuncture. A hose 24 provided with an adapter 26 at an end thereof isconnected to the bottle 22. The hose 2 connected to the air compressor 1is also provided with an adapter 9 at an end thereof. It should be notedthat, if the hose 24 for the bottle 22 is of a type directly connectableto the tire valve 10, the adapter 9 may be omitted.

When a tire is punctured, the adapter 26 for the bottle 22 is screwed onand attached to the tire valve 10. Thus, the bottle 22 communicates withinterior of the tire via the hose 24 and the adapter 26. In this state,an operator squashes the bottle 22, as shown by the double-dashed line(phantom line) in FIG. 2A, to squeeze out the puncture-sealant 6 fromthe bottle 22, so that the puncture-sealant 6 is injected into the tirethrough the hose 24.

When the injection of the puncture-sealant 6 from the bottle 22 into thetire is completed, the operator removes the adapter 26 from the tirevalve 10 to disengage the bottle 22 from the tire.

Subsequently, the operator screws on the adapter 9 of the air compressor1 to attach to the tire valve 10, so that the air compressor 1communicates with interior of the tire via the adapter 9 and the hose 2.In this state, the operator turns on the air compressor 1 to inflate thetire with pressurized air again until the tire has a predeterminedinternal pressure. When this procedure is completed, the operatorremoves the adapter 9 from the tire valve 10 and turns off the aircompressor 1. After this, running is immediately carried out over acertain distance to spread the puncture-sealant 6 inside the tire toseal a puncture hole. Subsequently, the operator connects the aircompressor 1 of the pumping-up device 30 again to pump up the tire untilit has a required internal pressure.

EXAMPLES

Hereinafter, the invention will be described more in details by way ofExamples. These Examples do not limit the invention.

Examples 1 to 3 and Comparative Examples 1 to 3

Materials shown in Table 1 below were mixed into NBR latex (Nipolemanufactured by ZEON Corporation) to prepare puncture-sealants ofExamples 1 to 3 and Comparative Examples 1 to 3.

It should be noted that, as the short fiber, nylon short fibers with aspecific gravity of 1.14, a diameter of 15 μm and a length of 4 mm wereused. Further, viscosities (viscosities at temperatures in the rangefrom 60° C. to −20° C.) of the puncture-sealants measured with a B-typeviscometer were within a range from 3 mPa·s to 6000 mPa·s.

Example 4

A puncture-sealant of Example 4 was prepared in the same manner as inExample 1, except that, before mixing the short fiber in the NBR rubberlatex, the short fiber was treated with a solvent employing a higheralcohol derivative (Emulon, manufactured by Meisei Chemical Works,Ltd.). A viscosity of the puncture-sealant (viscosity at temperatures inthe range from 60° C. to −20° C.) was within a range from 3 mPa·s to6000 mPa·s.

The treatment with the solvent was conducted in the following manner.First, an aqueous solution containing the higher alcohol derivative(solvent) was prepared. Then, the short fiber was immersed in the thusprepared aqueous solution, with the amount of the solvent being 3 partsby mass with respect to 100 parts by mass of the short fiber.

Example 5

A puncture-sealant was prepared in the same manner as in Example 1,except that, in place of the short fiber, a terpenephenol resin (YSPolystar manufactured by Yasuhara Chemical Co., Ltd., a content thereofin the puncture-sealant being 5% by mass) was included as a resinadhesive so that 5% of puncture-sealant (viscosity at temperatures inthe range from 60° C. to −20° C.) was within a range from 3 mPa·s to6000 mPa·s.

Example 6

A puncture-sealant was prepared in the same manner as in Example 1,except that the above terpenephenol resin (a content thereof in thepuncture-sealant being 5% by mass) was included as the resin adhesive sothat 5% of the 12% by mass of water was substituted with the resin. Aviscosity of the puncture-sealant (viscosity at temperatures in therange from 60° C. to −20° C.) was within a range from 3 mPa·s to 6000mPa·s.

100 g was collected from each of the puncture-sealants prepared inExamples 1 to 6 and Comparative Examples 1 to 3, and retained at 200° C.for 30 minutes. Thereafter, solid contents were calculated based on themasses after the 30 minutes. These solid contents are shown in Table 1below. Unless otherwise specified, the unit is “percent by mass” inTable 1. TABLE 1 NBR Nylon rubber Ethylene short Solid latex glycolWater fiber Additives* content Example 1 55 30 12 2 Some 35 (residual)Example 2 55 30 12 0.12 Some 33 (residual) Example 3 55 30 12 4.98 Some38 (residual) Example 4 55 30 12 3 Some 35 (residual) Example 5 55 30 12— Some 33 (residual) Example 6 55 30 12 1 Some 35 (residual) Comp. 55 3012 — Some 32 Ex. 1 (residual) Comp. 55 30 12 0.08 Some 32 Ex. 2(residual) Comp. 55 30 12 5.2 Some 38 Ex. 3 (residual)*Additives: a defoaming agent, a thickener, a pH controller

The prepared puncture-sealants were evaluated with respect to (1) thepuncture hole sealing ability, (2) the ease of injection, (3) theantifreezing property and (4) the separation stability, in the mannerdescribed below.

(1) Puncture Sealing Ability:

Using a drill, a hole of φ 1.5 mm was made in a tire tread groove of atire, and the puncture-sealant thus prepared was injected into the tireand the tire was mounted on a vehicle. Then, while maintaining an airpressure of 1.3 kgf/cm² (12.74×10⁻⁴ Pa), the vehicle was driven at aspeed of about 50 km/h, and a time required to completely stop airleakage was measured.

Regarding the measured time, the time required to complete sealing usingthe puncture-sealant of Comparative Example 1 was indexed as 100, thetime (X) required to complete sealing using each of thepuncture-sealants of Examples 1 to 6 and Comparative Examples 2 and 3was indexed by:X/(time of Comparative Example 1)×100,and the indices thus obtained were compared. Results are shown in Table2 below.(2) Ease of Injection:

Using a 100 ml syringe, each of the prepared puncture-sealants wasinjected through the valve. Taking the time required to inject thepuncture-sealant of Comparative Example 1 as a reference, a injectiontime within a range of ±20% of the injection time of Comparative Example1 was judged to be “acceptable”. Results are shown in Table 2 below.

(3) Antifreezing Property:

The prepared puncture-sealants were stored at −30° C. for 3 hours.Whether each of the puncture-sealants had frozen was visually evaluated,with the puncture-sealant which had not frozen being judged to be“acceptable”. Results are shown in Table 2 below.

(4) Separation Stability:

The prepared puncture-sealants were left at 60° C. for one month.Whether or not each of the puncture-sealants had separated was visuallyevaluated, with the puncture-sealant which did not exhibit separationbeing judged to be “acceptable”. Results are shown in Table 2 below.TABLE 2 Sealing Ease of Freezing Separation ability injection propertystability Example 1 28 Acceptable Acceptable Acceptable Example 2 32Acceptable Acceptable Acceptable Example 3 26 Acceptable AcceptableAcceptable Example 4 27 Acceptable Acceptable Acceptable Example 5 47Acceptable Acceptable Acceptable Example 6 24 Acceptable AcceptableAcceptable Comp. Ex. 1 100 — Acceptable Acceptable Comp. Ex. 2 100Acceptable Acceptable Acceptable Comp. Ex. 3 25 Unacceptable AcceptableAcceptable

As can be seen from the results in Table 2, the puncture-sealants ofExamples 1 to 6 which contained the short fiber are improved in sealingability. Further, by setting the solid content and the short fibercontent within the predetermined ranges, the ease of injection, theantifreezing property and the separation stability, which are as good asthose of the conventional puncture-sealants, can be obtained whilemaintaining high sealing ability. Thus, from these results, it isconfirmed that the puncture-sealant of the invention had excellentpracticality.

INDUSTRIAL APPLICABILITY

As described above, the puncture-sealant of the invention can maintainhigh sealing ability and can exhibit excellent practical performances.Therefore, the puncture-sealant of the invention is applicable topuncture repairing for various pneumatic tires, such as tires forautomobiles, two-wheeled vehicles, unicycles, wheelbarrows, wheelchairs,and agricultural and grounds-maintenance vehicles.

1. A puncture-sealant for sealing a hole in a punctured tire, thepuncture-sealing agent comprising: (1) at least one type of rubber latexselected from the group consisting of SBR latex, NBR latex, MBR latex,carboxyl-modified SBR latex and carboxyl-modified NBR latex; (2) anantifreezing agent; and (3) at least one of a short fiber and/or a resinadhesive that is compatible with the rubber latex.
 2. Thepuncture-sealant as claimed in claim 1, wherein the resin adhesive isadded to an aqueous dispersion of the rubber latex or an aqueousemulsion of the rubber latex.
 3. The puncture-sealant as claimed inclaim 1 , wherein a content of the resin adhesive is within a range from3 to 30% by mass.
 4. The puncture-sealant as claimed claim 1, wherein acontent of solid components is within a range from 5 to 70% by mass. 5.The puncture-sealant as claimed in claim 1, wherein a content of theantifreezing agent is within a range from 5 to 50% by mass.
 6. Thepuncture-sealant as claimed in any of claim 1, wherein a viscosity ofthe puncture-sealant at least before it is filled in the tire and attemperatures in the range from 60° C. to −30° C. is within a range from3 mPa·s to 6000 mPa·s.
 7. The puncture-sealant as claimed in any ofclaim 1, wherein a content of the short fiber is within a range from 0.1to 5% by mass.
 8. The puncture-sealing sealant as claimed in claim 7,wherein a length (L) of the short fiber is within a range of 0.05≧L≧10mm and a diameter (D) of the short fiber is within a range of 1≧D≧100μm.9. The puncture-sealant as claimed in any of claim 8, wherein a ratio(L/D) of the length (L) of the short fiber to the diameter (D) of theshort fiber is within a range of 5≧LD≧2000.
 10. The puncture-sealant asclaimed in an) of claim 9, wherein a specific gravity (S) of the shortfiber is within a range of 0.8≧S≧1.4.
 11. The puncture-sealant asclaimed in any of claim 10, wherein all or part of the short fiber istreated with a solvent.
 12. The puncture-sealant as claimed in claim 11,wherein the short fiber comprises one of polyester, polyethylene, nylon,polypropylene or a composite of two or more types thereof.
 13. Apuncture-sealant for sealing a hole in a punctured tire, thepuncture-sealant comprising: (1) at least one type of rubber latexselected from the group consisting of SBR latex, NBR latex, MBR latex,carboxyl-modified SBR latex and carboxyl-modified NBR latex; (2) anantifreezing agent; and (3) a short fiber, of which all or a part istreated with at least one of a higher alcohol derivative and a betainesurfactant.
 14. A puncture-sealant for sealing a hole in a puncturedtire, the puncture-sealant comprising: (1) at least one type of rubberlatex selected from the group consisting of SBR latex, NBR latex, MBRlatex, carboxyl-modified SBR latex and carboxyl-modified NBR latex; (2)an antifreezing agent; (3) a short fiber, of which all or part istreated with at least one of a higher alcohol derivative and a betainesurfactant; and (4) a resin adhesive that is compatible with the rubberlatex.